1. Field of the Invention
The present invention relates to a method of manufacturing sliders used for a thin-film magnetic head and the like and to a slider manufacturing aid used in a manufacturing process of sliders.
2. Description of the Related Art
A flying-type thin-film magnetic head used for a magnetic disk device and so on is generally made up of a thin-film magnetic head slider (that may be simply called a slider) having a thin-film magnetic head element provided at the trailing edge of the slider. The slider generally comprises a rail whose surface functions as a medium facing surface (an air bearing surface) and a tapered section or a step near the end on the air inflow side. The rail flies slightly above the surface of a recording medium such as a magnetic disk by means of air flow from the tapered section or step.
A thin-film magnetic head element generally used is a composite-type element made up of layers of an induction magnetic transducer for writing and a magnetoresistive (MR) element for reading.
In general, such thin-film magnetic head sliders are formed through cutting a wafer in one direction in which sections to be sliders (called slider sections in the following description) each including a thin-film magnetic head element are arranged in a plurality of rows. A block called a bar in which the slider sections are arranged in a row is thereby formed. Rails are then formed in the bar and the bar is cut into the sliders.
The manufacturing process of the sliders includes a step of processing the medium facing surface of the bar, that is, grinding or lapping the medium facing surface and a step of cutting the wafer into the bars. The order of the step of processing the medium facing surface and the step of cutting the wafer into the bars depends on methods of processing the medium facing surface and cutting the wafer, as described later.
In the step of processing the medium facing surface, it is required that the MR height and the throat height of the thin-film magnetic head element formed in the bar each fall within a tolerance range and that processing accuracy of the surface processed falls within a tolerance range. The MR height is the length (height) between the end of the MR element close to the medium facing surface and the opposite end. The throat height is the length (height) of the magnetic pole of an induction magnetic transducer.
In related art the following method is generally taken to process the medium facing surfaces of the bars and cutting the wafer into the bars. That is, a bar including a row of slider sections is cut from a wafer. The bar is fixed to a specific jig by bonding the surface of the bar opposite to the medium facing surface to the jig. The medium facing surface of the bar thus fixed to the jig is then processed. This method is called a first method in the following description.
In related art, second to sixth methods described below have been proposed, in addition to the above-described first method, for processing the medium facing surfaces of the bars and cutting the wafer into the bars.
The second method is, as shown in FIG. 7 of U.S. Pat. No. 5,406,694, for example, a specific length of block including rows of slider sections is cut from a wafer. The block is fixed to a specific jig by bonding the surface of the block opposite to the medium facing surface to the jig. The medium facing surface of the block thus fixed to the jig is then processed. The block is then cut into bars whose medium facing surfaces have been processed.
The third method is, as shown in FIG. 3 of Japanese Patent Application Laid-open Hei 4-289511 (1992), for example, a wafer is fixed to a specific jig and the medium facing surface of the wafer fixed to the jig is processed. The wafer is then cut into bars whose medium facing surfaces have been processed.
The fourth method is, as shown in FIG. 7 of Japanese Patent Application Laid-open Hei 4-289511, for example, a wafer or a block having a specific length and including rows of slider sections cut from a wafer is utilized. A reference surface opposite to the medium facing surface of the wafer or block is processed. The wafer or block is then fixed to a specific jig by bonding the reference surface to the jig. The wafer or block is cut at a position to be the medium facing surface. A bar is thus separated while fixed to the jig and the medium facing surface of the bar is processed.
The fifth method is, as shown in FIG. 8 and FIG. 9 of Japanese Patent Application Laid-open Hei 4-289511, for example, a wafer is utilized, having the slider sections formed such that medium facing surfaces of adjacent rows face each other or surfaces opposite to the medium facing surfaces of adjacent rows face each other. The wafer is cut at a position where the surfaces opposite to the medium facing surfaces face each other to obtain a block including two rows of slider sections. A specific jig is fixed to each end face of the block through the use of an adhesive. The block is then cut at a position where the medium facing surfaces face each other to separate the block into two bars each fixed to the jig. The medium facing surface of each bar is then processed.
The sixth method is, as shown in FIG. 10 and FIG. 11 of Japanese Patent Application Laid-open Hei 4-289511, for example, a wafer is utilized, having the slider sections formed such that medium facing surfaces of adjacent rows face each other or surfaces opposite to the medium facing surfaces of adjacent rows face each other. The wafer is cut at a position where the medium facing surfaces face each other to obtain a block including two rows of slider sections. A specific jig is fixed to one medium facing surface of the block through the use of an adhesive. The other medium facing surface of the block is then processed. A specific jig is fixed to the other medium facing surface thus processed through the use of an adhesive. The jig is detached from the one medium facing surface and this medium facing surface is processed. The block is cut at a position where the surfaces opposite to the medium facing surfaces face each other to separate the block into two bars.
Of the foregoing methods, in the first method a bar including a row of slider sections is cut from a wafer. The bar is fixed to a jig and the medium facing surface of the separated bar is then processed. Consequently, the bar is often affected by the state of the interface between the bar and the jig or by warpage caused by bonding and likely to be deformed and to form a curvature and the like. As a result, it is likely that processing accuracy of the surface of the bar processed is reduced and deformation occurs, such as curvatures of the layers making up the thin-film magnetic head elements formed in the bar. In addition, it is difficult to precisely control the resistance of the MR element, the MR height and the throat height. It is therefore difficult to precisely fabricate thin-film magnetic head sliders with excellent properties.
In the fifth and sixth methods, a block including two rows of slider sections is cut from a wafer and the block is fixed to the jig. In this case, too, problems similar to those of the first method described above may result since the block is thin and easy to deform.
In contrast, the second to fourth methods do not include the step of fixing a separate bar or block including two rows of slider sections cut off from a wafer to the jig. Therefore, the above-stated problems are reduced. However, those problems arise in those methods, too, when bars continue to be cut from a wafer or block and the number of rows of slider sections remaining in the wafer or block is reduced. In the third and fourth methods, in particular, every time a bar is separated, the bar or block is fixed to the jig or the bar or block is detached from the jig. Consequently, it is required that a separate thin block including the small number of rows of slider sections is fixed to the jig when bars continue to be cut from the wafer or block and the number of rows of slider sections remaining in the wafer or block is reduced. The above-described problems therefore become remarkable.
Furthermore, in the third and fourth methods, every time a bar is separated, the step is required for fixing the wafer or block to the jig or detaching the bar or block from the jig. The manufacturing process is thereby complicated and the production efficiency is reduced. In the third method, the shape of the wafer as an object whose medium facing surface is processed is changed, depending on the number of rows of slider sections remaining in the wafer. Consequently, handling of the wafer is inconvenient when the medium facing surface is processed. In addition, the length of the bar separated varies. As a result, handling for transferring the bar to the post-step or handling of the bar in the post-step is inconvenient.
In any of the first to sixth methods, the bar whose medium facing surface has been processed is detached from the jig and separately transferred to the post-step. Therefore, a transfer arm or a member for fixing the bar directly touches the bar when the bar is transferred to the post-step or handled in the post-step. Damage to the thin-film magnetic heads thereby frequently results.